3D printing, as a popular concept, is a kind of rapid prototyping technologies produced in the late 1980s. This technology, as the integration of mechanical engineering, material engineering, numerical control technology, laser technology and so on, manufactures prototype parts by material accumulation. The principle is to form a digital model by the modeling based on the computer aided design (CAD) or computer animation, resolve the 3D model into two-dimensional cross sections layer by layer, and then produce an entity product by accumulating and solidifying the printing material layer by layer with a software and a numerical control system. Primary methods include Stereo Lithography Apparatus (SLA), Laminated Object Manufacturing (LOM), Selective Laser Sintering (LS), Fused Deposition Modeling (FDM) and so on.
Compared with traditional manufacturing methods, 3D printing technology has the advantages comprising manufacture without being limited by the shape complexity of the product parts, rapid manufacture, feasibility for the synchronization of product design and mold production, improved research and development efficiency, shorten design cycle and high utilization rate (nearly 100%) of raw materials. Based on the above advantages, this technology has been widely applied in the fields such as automotive, household electrical appliances, communication, aviation, industrial modeling, medical treatment and archaeology.
The materials for 3D printing have been developed from the photosensitive resin, ABS, ABS classes, wax types, glass fiber and other plastic material, to stainless steel, aluminum alloy, iron nickel alloy, cobalt chromium molybdenum alloy and other metal materials. Although the material species have been richer than the past, a gap still exists as compared with the traditional materials used in manufacturing. Because some polymer materials have similar melting temperature and decomposition temperature, in order to avoid the change of the properties of the processed materials, the precise control of the processing temperature for improving the rate of finished products of the molding technology, has become an important technical problem to be solved.
UV laser has the advantages such as short wavelength, high resolution, concentrated energy focusing, stable pulse and high repetition frequency. Furthermore, it has the characteristic of “cold processing” which allows the direct destruction of the chemical bond of connecting material without producing external heat to periphery. Generally, the processes using ultraviolet laser could produce good finished surfaces, most of which do not have hot cracking and melting sediment, and have sharp and neat edges, refined microstructure, small and even negligible heat affected zone. Thus, the ultraviolet laser has become an ideal tool for processing fragile materials to obtain very high processing quality and dimensional precision. At the same time, since most materials, such as ceramics, metals, polymers, etc., could effectively absorb ultraviolet light, the ultraviolet laser has become an important band of 3D laser printing technology.
The patent application with the Publication Number of CN1135731 disclosed the method using a dual-beam laser to reduce material crimp caused by the excessive difference of temperature gradient. However, such laser needed a device with a complicated structure. Accordingly, the present disclosure provides a more simple method with lower cost for achieving even temperature gradient.